Temperature indicator and control



Sept. 4, 1934. E. s $M|TH 1,972,168

TEMPERATURE INDICATOR AND CONTROL Filed, Sept. 14, 1932 intentecl ept. 4, 1%354 hiiTE STATES PAT TEMPERATURE INDZCATQR AND CONTROL Elmore S. Smith, Weston, Ontario, Canada, as-

signer to Moiiats Limited, Weston, Ontario, Canada Application September 14, 1932, Serial No. 633,131 lln Canada May 4, 1932 3 Claims. l, 200-138) vice of this character in ch the number of the apparatus is rated.

are reduced to a minimum and in which colouring the periphery reg .tion is readily effected. trasting colours co-acts wit I attain my obicts b providing a therrncthe temperature of statically controlled to I. a cam track on runs. This roller is ried by a switch can 'e which tiltabiy mounted on regulator. Preferably a make 2 of ak mercury switch is en1- ployed, t switch being closed when in a hori- J -perature indicator havan anti-friction roller cured to the adjacent end of the tube other end of the spindle 4 above the secured a .icator 6 whi h is formed l or disk having a hub 6 in which is threaded d grub screw 7 "for engagement with the 1 The front of the base plate is curved at l co centric to the indicator and this curved portion is also inclined and providd with a dial 8 which. is graduated with the degr the chan which the thermostatic coil is plate 1 is secured to the top 0' the oven at the back thereof in any suitable runner.

On the upper end of the spindle 3 i" journalled a regulator 10 which is extended radially over an are shaped support 11 and is provided with zontal pc on and open in a tilted position. The index finger 10 positioned above the dial 8. A positions of the switch are controll d respecfriction device, formed by a fiat spring l2 tively by the low and high portions of the cam secured to the underside of the regulator, en ages track. By moving the regulator, the distance bethe underside of the support 11. A projection tween the high potion oi the cam track and 12 formed on the support to engage the anti-friction on the switch carrier is the spring arm to limit the movcnlent of the varied to vary the amount of travel of inulator in one direct on of travel. A switch cardicator relative to the regul *or before the switch rier 13 journalled by means of trunnions 14 on is opened. The oven is me lned at the temthe regulator is provided with clips 15 for receivperature set by regulator by the to and fro ing a mercury switch 16 of known construction.

3 movement of high portion on the ih- This type of switch comp ises two contacts adaptdicator relative to roller on the switch cared to be electrically connected by a globule of rier whereby a slight drop in temperature will mercury when the switch is a horizontal posicause the switch to be closed and a corresponding tion. When the switch is tilted the mercury runs rice in temper uore will open the switch. to one end and thus breaks the connect-ion be- The constructions hereinafter more fully tween the contacts. These contacts are connect-- described and are illustrated in the accompanyed in a wire 17, 1'7 of a circuit for supplying elecing drawing which: trical energy to the heating element or elements Fig. l is a plan view of apparatus, th cover of the oven. being removed; The carrier 13 is provided with a leg 13 having 49 2 a vertical section on the line 22 in an anti-friction roller 18 journalled thereon for Fig. 1; engagement with a cam track 19 on the indicator Fig. 3 a cross section on the line 33 in Fig. 6. The cam track has a high portion 19 and a 1; and low portion 19*, the latter being forms by the Fig. 4 a detail in end elevation of the switch upper surface of the indicator. An inclined face carrier and track. 19 on the cam track facilitates the travel of the In the drawing like numerals or" reference inhigh portion 19 beneath the roller 18 which dicate corresponr ng arts in the different figcauses the switch to be tilted to its open position. ures. Assuming the switch 13 to be in its normally 1 is a base plate the un rside of which is pro closed position with the roller l8" engaging the vided with a boss 2 in which is secured a tube 3. low portion 19 of the cam track, the mode of A spindle i passes through the tube and boss operation is as follows. The index finger or" and jcurnalled therein in any suitable manthe regulator 10 is turned to the degree of heat ner. One end of oi-metallic thernicstatic coil 5 marked on the dial 8 which it is desired to maindisposed on the spindle is secured to the lower tain. When the main switch (not shown) of the end thereof and the other end of the coil is secircuit (including the wire 17, 1'7 for supplying current to the heating element or elements in the oven is closed, the rise in temperature causes the thermostatic coil 5 to turn the spindle 4 and thus the indicator 6 whereupon the pointer 6 moves across the dial 8 towards the index finger 10 and the inclined face 19 moves towards the antifriction roller 18 As the pointer 6 nears the regulator index finger 10 the inclined face 19 passes under the roller 18 and, when the pointer 6 registers with the index finger ic the high portion l9 of the cam track 19 engages the roller 18 to tilt the mercury switch 16 to its open position. The current is thus cut ofi independently of the main switch and as the temperature of the oven drops slightly the direction of rotation of the indicator 6 is reversed whereby the roller 18 travels down the inclined face 19 to cause the mercury switch to be closed again. The switch is thus alternately opened and closed to maintain 1 the oven at the desired temperature.

Referring to Fig. 1 it will be noted that as the regulator index finger 10 is moved either towards the low or the high figures on the dial 8, the leg 18 and its roller 18 are moved towards and away from the inclined face l9 respectively. The amount of travel of the inclined face 19 relative to the roller 18 is thus varied directly in proportion to the travel of the pointer 6 relative to the regulator index finger 10 The high portion 19 of the cam track 19 subtends an arc of substantially 180 so that the apparatus may be immediately set to maintain the oven at a desired temperature lower than the temperature to which it had been originally raised.

What I claim as my invention is:

1. A. temperature indicator and control comprising a rotatable spindle; thermostatic means for controlling the rotary movements of the spindle; a disk secured to the spindle; indicating means comprising a pointer carried by the disk and a dial; a cam track on said disk; a regulator journalled on said spindle; a normally closed fiuid contact switch; and a carrier for said switch pivoted directly on the regulator to tilt relative thereto, the switch carrier being engaged directly by the cam track to cause it to open the switch, the regulator being adapted to move the switch carrier relative to the cam track so that the extent of movement of the cam track relative to the carrier necessary to cause the switch to open or close may be varied.

2. A temperature indicator and control comprising a rotatable spindle; thermostatic means for controlling the rotary movements of the spindle; a disk secured to the spindle; indicating means comprising a pointer carried by the disk and a dial; a cam track on said disk; a regulator journalled on said spindle; a normally closed fluid contact switch; a carrier for said switch pivoted at one end thereof directly on the regulator to tilt relative thereto, the switch carrier having a leg on the end thereof remote from that pivoted on the regulator; and an anti-friction roller carried said leg for direct engagement with the cam track to cause it to open the switch, the regulator being adapted to move the switch carrier and roller relative to the cam track so that the extent of movement of the cam track relative to the roller necessary to cause the switch to open or close may be varied.

3. A temperature indicator and control comprising a rotatable spindle; thermostatic means for controlling the rotary movements of the spindle; a disk secured to the spindle; indicating means comprising a pointer carried by the disk A latter being engaged directly by the cam track to cause it to open and close the switch, the trunnions being adapted to revolve the switch carrier with the regulator on its axis around the cam track so that the extent of movement of the latter relative to the carrier may be varied to adjust the opening and closing of the switch.

ELMOEE S. SMITH. 

